Background: Obesity prevalence has been increasing while cardiometabolic mortality has been decreasing. The reasons for this paradox are not fully understood.
Aim: To test the hypothesis that the prevalence of metabolically healthy obesity (MHO) in the U.S. adult population increases over time.
Methods: The study included 16,459 participants of the National Health and Nutrition Examination Survey (NHANES) 1999-2014. MHO was defined as central obesity (waist circumference≥102 cm for men and ≥88 cm for women) without any of the following conditions: elevated levels of blood pressure (<125/85 mm Hg), glucose (<100 mg/dL), and triglycerides (<150 mm/dL), reduced levels of high-density lipoprotein cholesterol (≥40 mg/dL for men and ≥50 mg/dL for women), and any medication use for high cholesterol, hypertension, or diabetes.
Results: The prevalence of central obesity increased from 45.17% in 1999-2000 to 56.72% in 2013-2014 (P=0.003). MHO prevalence increased from 4.95% in 1999-2000 to 8.92% in 2013-2014. Among those with central obesity, the proportion of MHO increased from 11.0% in 1999-2000 to 15.7% in 2013-2014. Female gender, a younger age, being Hispanic and non-Hispanic Black, and high education (some college or above) were associated with higher prevalence of MHO.
Conclusions: While the prevalence of central obesity in the U.S. population has increased, the prevalence of MHO and the proportion of MHO among those who are centrally obese have also increased since 1999, which may partly contribute to the paradox between increased obesity prevalence and reduced cardiometabolic mortality.